Spark plug



April 2, 1940. c. M. SONGER SPARK PLUG Filed June 26, 19259 .4 Horm'ys Patented Apr. 2, 1940 UNITED STATES PATENT OFFICE 1 Claim.

The present invention relates to new and useful improvements in spark plugs and has for its primary object to provide, in a manner as hereinafter set forth, a device of this character em- Another very important object of the 'invention is to provide a spark plug of the aforementioned character embodying a construction and arrangement which is such that it may be expeditiously assembled or disassembled and wherein the adjustable positive electrode may be removed for replacement when necessary.

Other objects of the invention are to provide a spark plug of the character described which will be comparatively simple in construction, strong, durable, highly efiicient and reliable in use, compact and which may be manufactured at low cost.

All of the foregoing and still further objects and advantages of the invention will become apparent from a study of the following specification, taken in connection with the accompanying drawing wherein like characters of reference designate corresponding parts throughout the several views, and wherein:

Figure 1 is a view in vertical section through a spark plug constructed in accordance with the present invention.

Figure 2 is a top plan view of the device.

Figure 3 is a bottom plan view.

Referring now to the drawing in detail, it will be seen that the embodiment of the invention which has been illustrated comprises a metallic shell I which is adapted to be screwed in the usual manner into the engine, said shell having its lower portion externally threaded, as at 2. Mounted on the lower end of the shell I is a negative electrode 3 having an enlarged free end portion 4.

The reference numeral 5 designates a porcelain core which is firmly secured in the shell I through the medium of a nut 6. Molded in the upper portion of the porcelain core 5 is an internally threaded metallic bushing I.

The reference numeral 8 designates a positive electrode which extends vertically through the porcelain core 5. The positive electrode 8 comprises an enlarged, threaded upper portion 8 which is threadedly mounted for adjustment in I the bushing I.

a removable cap I2 which is adapted to receive the usual terminal (not shown) of a spark plug wire. The upper end of the positive electrode 8 has formed therein a kerf I3 for receiving a screw driver or other suitable tool.

It is thought that the manner in which the spark plug functions will be readily apparent from a consideration of the foregoing. Of course, the current flows through the cap,l2 and the positive electrode 8 and jumps the gap to the negative electrode 3 and is grounded to the engine through the shell 2. The enlarged free end portion 4 greatly prolongs the life of the negative electrode 3. To adjust the positive electrode 8 toward or away from the negative electrode 3, the cap I2 is removed and the lock nut I0 is loosened. Then, by engaging a screw driver or other suitable tool in the kerf I3 the electrode 8 may bescrewed inwardly or outwardly in the bushing l for decreasing or increasing the gap between said electrode 8 and the electrode 3. The threads of the elements I and 9 are to be of a predetermined pitch such, for example, as 20 or 40 to the inch. Thus, by giving the positive electrode 8 a half or full turn it may be adjusted in either direction a predetermined distance. When the desired adjustment has been made the lock nut III is tightened and the cap I2 is replaced.

It is believed that the many advantages of an adjustable spark plug ccnstructed in accordance with the present invention will be readilly understood and although a preferred embodiment of the device is as illustrated and described, it is to be understood that changes in the details of construction and in the combination and arrangement of parts may beresorted to which willfall within the scope of the invention as claimed.

What is claimed is: I

A spark plug comprising a metallic shell, a negative electrode mounted on said shell, a core of insulating material mounted in the shell, an internally threaded bushing fixed longitudinally in the core, a positive electrode extending through the core and cooperable with the negative electrode, said positive electrode comprising an enlarged portion threadedly engaged with the bushing for adjustment toward and away from the negative electrode, said enlarged portion of the positive electrode projecting from one end of the bushing and having a kerf therein for receiving an adjusting tool, a lock nut threadedly mounted on the enlarged portion of the positive electrode for releasably securing said positive electrode in adjusted position, and a cap removably mounted on the projecting end portion of the enlarged portion of thepositive electrode.

' CLIFFORD M. SONGER. 

